1. Field of the Invention
The present invention relates to a depth dose measuring device to measure a depth dose in the human body, used to determine operating conditions of a cancer curing device using particle beams or corpuscular radiations such as an electron beam, X ray and the like.
2. Description of the Prior Art
FIG. 8 is a diagram showing a conventional method of measuring a depth dose distribution. In the drawing, reference number 104 denotes a water phantom accommodated in a container 105, 102 is an ionization chamber disposed in the water phantom 104, 103 is an amplifier to amplify an absorbed dose signal obtained from the ionization chamber 102, and 101 is a particle beam or a corpuscular beam with which the water phantom 104 is irradiated.
In the conventional depth dose measuring device having the structure shown in FIG. 8, the ionization chamber 102 disposed in the water phantom 104 measures an absorbed dose at a disposed position. The ionization chamber 102 is moved in a depth direction A and in a direction perpendicular to a beam axis C of the particle beam, that is, in a horizontal direction B, thereby measuring the absorbed dose distribution. The amplifier 103 is used to amplify and measure the amount of ionization obtained by the particle beam 101 ionizing air in the ionization chamber 102 disposed in the water phantom 104. In order to measure the absorbed dose distribution, the ionization chamber 102 is moved in the depth direction A and in the horizontal direction B, and the amount of ionization is measured for each movement.
The conventional depth dose measuring device has the above structure. Thus, in order to measure the depth dose distribution, it is necessary to move the ionization chamber 102 in the water phantom 104 for each measurement, resulting in requiring an extremely long time and a lot of labor. Further, three-dimensional dose distribution measurement requires a vast amount of time and labor.
Further, when a variation is caused in the output of a particle beam irradiation device such as an electron beam irradiation device, or X ray irradiation device, the depth dose must be measured from the beginning once again. Thus, the depth dose measurement requires an extremely long time and a lot of labor.